Nanomaterials with tetrazole-based removable stabilizing agents

ABSTRACT

Nanoparticles coated with tetrazole and methods for preparing them are provided. The nanoparticles can be coated onto a substrate and used in fabricating devices such as field effect transistors, switches, sensors, solar cells and spring exchange magnets.

TECHNICAL FIELD

The present disclosure relates to nanoparticles and more particularly to nanoparticles having a shell or coating of a material that can be removed after integrating the nanoparticles into a device. The compounds act to stabilize the nanoparticles to prevent undesirable fast growth and coagulation with other particles.

BACKGROUND

One of the challenges of contemporary solid-state electronics is the depositing of thin semiconducting films with high carrier mobility via convenient and high throughput solution-based techniques like spin-coating and ink-jet-printing [D. B. Mitzi, J Mater. Chem., 2004, 14, 2355; A. Zaslavsky, Appl. Phys. Lett. 2003, 83, 1653; S. R. Forrest, Chem. Rev. 1997, 97, 1793]. The need for solution-processable electronic components motivated the development of molecular electronics employing organic components (e.g., in thin-film transistors [Thin-Film Transistors, Eds. Kagan, C. R. & Andry, P., Marcel Dekker, New York, 2003.]). The solution-phase processing of active electronic elements from inorganic semiconductors could be very promising because of significantly higher carrier mobility in inorganic semiconductors compared to the organic ones. Recently, Mitzi et al. reported the semiconducting SnS_(2-x)Se_(x) films formed by spin-coating, which exhibit n-type transport with mobility about 10 cm²V⁻¹s⁻¹ [D. B. Mitzi, L. L. Kosbar, C. E. Murray, M. Copel, A. Afzali, Nature, 2004, 428, 299.]. This mobility is an order of magnitude higher than previously reported values for spin-coated semiconductors. However, it is still many orders of magnitude lower than the carrier mobilities in bulk semiconductors and in thin films prepared by vacuum deposition techniques. The low carrier mobilities observed in semiconducting films prepared by low-temperature solution-based techniques are usually attributed to their low purity and poor crystallinity. Overcoming this problem is the important challenge, with the resulting expectations of low-cost device fabrication. These novel techniques may find use in the fabrication of a variety of thin-film based devices (for example, field-effect transistors, solar cells) which, in turn, can be employed in a variety of commercial products such as flexible or wearable computers, large-area high-resolution displays etc.

During last few years, significant progress has been achieved in chemical synthesis of semiconductor quantum dots by the methods of colloidal chemistry. Colloidally grown nanoparticles comprise a crystalline core surrounded by a layer of surfactant molecules. The molecules of surfactant (further referred to as “stabilizing agents” or “stabilizers”) bind to the nanoparticle surface immediately after nanoparticlesl nucleation to prevent its fast growth and coagulation with other particles. The shell of stabilizing agents attached to the nanoparticles surface determines solubility of nanoparticles in a desired (e.g., polar or non-polar) solvent [N. Gaponik, D. V. Talapin, A. L. Rogach, A. Kornowski, A. Eychmüller, H. Weller. Nano Lett. 2002, 2, 803.]. The modem chemical approaches allow obtaining various materials in form of monodisperse nanoparticles with controllably tunable size and shape (e.g. nanospheres, nanorods, etc.) [C. B. Murray, C. R. Kagan, M. G. Bawendi, Annu. Rev. Mater. Sci. 2000, 30, 545; H. Weller, Angew. Chem. Int. Ed. Engl. 1993, 32, 41; X. Peng, L. Manna, W. D. Yang, J. Wickham, E. Scher, A. Kadavanich, A. P. Alivisatos, Nature, 2000, 404, 59.]. Moreover, nanomaterials comprising more than one phase, e.g., core-shells, dumbbells have been prepared by means of solution phase reactions.

The use of colloidally grown semiconductor nanoparticles as precursors for semiconducting films is promising because: (i) semiconductors with low effective mass and high carrier mobility, e.g., InAs, InP, PbSe, PbTe, can be synthesized in the form of monodisperse nanoparticles; (ii) the nanoparticles usually have nearly defect-free crystalline cores; (iii) sintering of individual nanoparticles into a film is facilitated by significant reduction of the nanoparticles melting temperature along with decreasing its size [A. N. Goldstein, C. M. Echer, A. P. Alivisatos, Science, 1992, 256, 1425.] and such can occur through the mechanism of oriented attachment [R. L. Penn, J. F. Banfield, Geochim. Cosmochim, Acta, 1999, 63, 1549; C. Pacholski, A. Kornowski, H. Weller, Angew. Chem. Int. Ed., 2002, 41, 1188; Z. Tang, N. Kotov, M. Giersig, Science, 2002, 297, 237]; (iv) mixing colloidal solutions of different nanoparticles allows formation of various composite materials [F. X. Redl, K. -S. Cho, C. B. Murray, S. O'Brien, Nature, 2003, 423, 968]; (v) employing the nanoparticles with shape anisotropy (nanorods, nanowires) allows preparation of materials with anisotropic properties [D. V. Talapin, E. V. Shevchenko, C. B. Murray, A. Kornowski, S. Forster, H. Weller, J. Am. Chem. Soc, 2004; 126, 12984.].

To be used in electronic circuits, the nanoparticles should be electrically addressable. However, the previous studies revealed extremely poor conductivities of layers of close-packed nanoparticles [N. Y. Morgan, C. A. Leatherdale, M. Drndić, Mirna V. Jarosz, M. A. Kastner, M. G. Bawendi Phys. Rev. B, 2002, 66, 075339; M. Drndić, M. V. Jarosz, N. Y. Morgan, M. A. Kastner, M. G. Bawendi, J. Appl. Phys., 2002, 92, 7498]. The nanocrystal layers exhibit low conductivities because each colloidally grown nanoparticle is surrounded by an insulating shell of stabilizing agents. The reported attempts of complete removal of stabilizing agents (phosphines, phosphine oxides) by heating the nanoparticle layers in vacuum were unsuccessful because of partial destruction and carbonization of surfactant molecules at high temperatures [M. Kuno, J. K. Lee, B. O. Dabbousi, F. V. Mikulec, M. G. Bawendi J. Chem. Phys. 1997, 106, 9869.]. Sintering individual nanoparticles into a polycrystalline film increases film conductance but leaves multiple structural defects that limit the device switching speeds [B. R. Ridley, B. Nivi, J. M. Jacobson, Science 286, 746 (1999)]. At the same time, the experiments with semiconductor nanowires and carbon nanotubes demonstrate the extremely high carrier mobility in confined structures [X. Duan, C. Niu, V. Sahi, J. Chen, J. W. Parce, S. Empedocles, J. L. Goldman, Nature, 2003, 425, 274].

There are some reported attempts of chemical removal of stabilizing agents, for example, by treating semiconducting nanoparticles with NaOH [M. B. Jarosz, V. J. Porter, B. R. Fisher, M. A. Kastner, M. G. Bawendi, Phys. Rev. B 70, 195327 (2004)] or hydrazine [D. V. Talapin, C. B. Murray Science 310, 86 (2005)]. These techniques, although improving electronic properties, does not allow complete removal of stabilizing agents.

The presence of stabilizing agents around nanoparticles negatively affects not only electronic, but some other properties of semiconductor, magnetic or catalytic nanoparticles, thus limiting their applications. The methods for reliable removal of stabilizing agents from nanoparticle surface are of interest for different nanomaterials and can be employed in a variety of applications.

In addition to the above discussed nanoparticle-based electronic devices, performance of solar cells based on semiconductor nanoparticles [W. U. Huynh, J. J. Dittmer, A. P. Alivisatos, Science, 2002, 295, 2425; I. Gur, N. A. Fromer, M. L. Geier, A. P. Alivisatos Science 2005, 310, 462.] is limited by slow transport of photoexcited charge carriers between the nanoparticles or by slow transport of holes from nanoparticle to the polymer matrix. Employing the nanoparticles with removable stabilizing agents, should improve the charge transport between nanoparticles and polymer matrix. Ink-jet printable highly conductive films can be formed from noble metal nanoparticles capped with removable stabilizing agents. The removable stabilizing agents are interesting for many other nanoparticle-based applications such as spring exchange magnets [H. Zeng, J. Li, J. -P. Liu, Z. L. Wang, S. Sun, Science 2000, 290, 1131, magneto resistive sensor, catalysts [S. U. Son, Y. Jang, J. Park, H. B. Na, H. M. Park, H. J. Yun, J. Lee, T. Hyeon, J. Am. Chem. Soc. 2004; 126, 5026], thermoelectric elements on low-dimensional materials [L. D. Hicks, M. S. Dresselhaus, Phys. Rev. B., 1993, 47, 16631.], ferroelectric memory elements, and the like.

SUMMARY

The present disclosure addresses problems encountered in prior techniques and provides nanoparticles where the shell of stabilizing ligands can be at least substantially or completely removed after integrating the nanoparticles into a device. According to the present disclosures the nanoparticles are coated with tetrazole- based compounds as stabilizing agents, which can be controllably destroyed by either mild thermal or chemical treatments. The nanoparticles coated with specially designed removable stabilizing agents can be attached to the nanoparticle surface either during the nanoparticle growth or by post-preparative exchange of surface ligands.

More particularly, the present disclosure is concerned with a nanoparticles capped or coated with a tetrzole represented by the formula:

wherein each R individually is selected from the group consisting of H, NH₂, NR′R′, SH, C₁-C₉ alkyl and C₁-C₉ alkyl substituted with at least one member selected from the group consisting of halogen, NH₂ SH and COOH and when substituted with COOH the substitution is on the end carbon atom farthest from the nitrogen of the tetrazole ring, each R′ individually is selected from the group consisting of H and C₁-C₄; and wherein at least one R group is H.

Another aspect of the present disclosure is a method for preparing the nanoparticles disclosed above which comprises adding the tetrazole during the synthesis of the nanoparticles.

A still further aspect of the present disclosure is a method for preparing the nanoparticles disclosed above which comprises adding the tetrazole after synthesis of the nanoparticles.

The present disclosure also relates to an article comprising a substrate and a layer of the nanoparticles disclosed above coated on the substrate.

A still further aspect of the present disclosure relates to a method for fabricating an article which comprises depositing on a substrate, a layer of the above disclosed nanoparticles.

Another aspect of the present disclosure is concerned with a method for fabricating a device which comprises depositing on a substrate, a layer of the above disclosed nanocrystal particles, then removing the tetrazole from the surface of the nanoparticles; and then sintering the nanoparticles. The sintering can be either a separate step, occur along with or immediately following the removal step, depending on the heating regime.

Examples of suitable devices are field effects transistors; sensors, switches, solar cells, and spring exchange magnets.

Still other objects and advantages of the present disclosure will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described only the preferred embodiments, simply by way of illustration of the best mode. As will be realized, the disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the disclosure. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.

SUMMARY OF DRAWINGS

FIG. 1 is a schematic diagram of fabrication of a field effect transistor with a channel made from sintered semiconducting nanoparticles with a removable tetrazole stabilizing agents according to the present disclosure.

FIG. 2 is a transmission electron microscopy (TEM) of nanoparticles stabilized with a tetrazole according to the present disclosure.

FIGS. 3 a-3 d show: (a) High-resolution TEM image of a film of CdS nanoparticles stabilized with 5-aminotetrazole and (b) corresponding selected area electron diffraction pattern. (c) High-resolution TEM image of the same film of CdS nanoparticles after annealing at 230° C. and (d) corresponding selected area electron diffraction pattern.

BEST AND VARIOUS MODES

According to the present disclosure, nanoparticles are coated with a tetrazole represented by the formula:

wherein each R individually is selected from the group consisting of H, NH₂, NR′R′, SH, C₁-C₉ alkyl and C₁-C₉ alkyl substituted with at least one member selected from the group consisting of halogen, NH₂ SH and COOH and when substituted with COOH the substitution is on the end carbon atom farthest from the nitrogen of the tetrazole ring, each R′ individually is selected from the group consisting of H and C₁-C₄; and wherein at least one R group is H. More typically the alkyl or substituted group contains 1-6 carbon atoms and even more typically contains 1-3 carbon atoms. The tetrazole compounds employed according to the disclosure are typically decomposed at temperatures of about 100° C. to about 350° C. and more typically at temperatures of 150° C. to about 280° C. without leaving solid residue.

Tetrazoles employed according to this disclosure are known and can be prepared by known techniques which need not be disclosed herein in any further detail. For instance, the synthesis of 5-alkyltetrazoles can be performed by the cycloaddition of azides to aliphatic nitriles [R. N. Butler in Comprehensive Heterocyclic Chemistry II: Eds-in-Chief A. R. Katritzky, C. W. Rees; E. F. V. Scriven. N. -Y Pergamon, 1996. -Vol. 4. Chapter 4.17. -P. 621-678; R. J. Herr, Bioorg. Med. Chem., 2002, 10, 3379.].

1-alkyl-5-mercaptotetrazoles (R═CH₃(CH₂)_(n), n=0-5) can be synthesized by cycloaddition of azides to thiocyanates [R. N. Butler in Comprehensive Heterocyclic Chemistry II: Eds-in-Chief A. R. Katritizky, C. W. Rees, E. F. V. Scriven. N. -Y: Pergamon, 1996. -Vol. 4. Chapter 4.17. -P. 621-678.].

The particle size of the nanoparticles are typically about 1.5 to about 20 nanometers and more typically about 3 to about 12 nanometers.

Typical examples of semiconductor nanoparticles are Si, Ge, Sn, Se, Te, B, P, As, Sb, Bi, AlN, AlP, AlAs, AlSb, GaAs, GaP, GaSb, InN, InP, InAs, InSb, CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, SnO, SnS, SnSe, SnTe, HgS, HgSe, HgTe, GeS, GeSe, GeTe, PbO, PbS, PbSe, PbTe, Sb₂S₃, Sb2Se₃, and Sb₂Te₃ and combinations thereof.

Typical examples of magnetic nanoparticles are Fe, Co, Ni, and all binary and ternary alloys of these. Fe, Co, Ni and alloys of these with any combination of Y, Zr, Nb, Mo, Ru, Rh, Pd, Pt, Pr, Nd, Sm, Gd, B, Al, and Si. In addition to magnetic oxides of the form Fe₂O₃, Fe₃O₄, CO₃O₄, CrO₂ and all substituted ferrites (M_(x)Fe_((2-x))O₄) where M=Mn, Co, Ni, Be, Mg, Ca, Sr, Ba, Zn, Cd, Sm, Y. Additional nanoparticle of mixed ferrites of the form M1_(x)M2_(y)Fe_((2-x-y))O₄ where M1 and M2 are selected from Mn, Co, Ni, Be, Mg, Ca, Sr, Ba, Zn, Cd, Sm, and Y.

Typical examples of ferroelectric and high dielectric and piezoelectric nanoparticles: BaTiO₃, SrTiO₃, Ba_(x)Sr_(1-x)TiO₃, PbTiO₃, Pb_(x)Zr_((1-x))TiO₃, LiNbO₃, antimony sulfo-iodide (SbSI), antimony sulfo-chloride (SbSCI) and antimony sulfo-bromide (SbSBr), GeTe, BiMnO₃, SrBi₂Ta₂O₉,

Typical catalytically active nanoparticles: V, Cr, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Pd, Ag, W, Re, Os, Ir, Pt, Au, and alloys of these as well as their corresponding oxides. Some catalytically active oxides TiO2, ZnO, BaO, CeO₂, Ce₂O₃, MoS₂,

Stable colloids of nanoparticles can be prepared using existing colloidal chemistry methods. The nanoparticles are easily processable in the form of colloidal solutions via common solution-based techniques. The nanoparticles of different II-VI, IV-VI and III-V compounds can be synthesized via the reactions shown below:

II-VI nanoparticles can be prepared in aqueous solutions by metathesis (reaction 1) [N. Gaponik, D. V. Talapin, A. L. Rogach, K. Hoppe, E. V. Shevchenko, A. Kornowski, A. Eychmüller, H. Weller, J. Phys. Chem. B, 2002, 106; 7177.]. The presence of different thiols (thioethanol, thioglycerol, thioglycolic acid, dithioglycerol, mercaptoethylamine, L-cysteine, etc.) as stabilizing agents and capping ligands allows controlling the particle size (size range of 2.0-8.0 nm is generally possible) during the synthesis. The advantages of the aqueous synthesis are its low cost, reproducibility and the simplicity of up-scaling. In this type of synthesis, the aqueous medium, if desired, can be replaced with other polar solvents (e.g., N,N-dimethylformamide, acetonitrile) [A. L. Rogach, A. S. Susha, F. Caruso, G. B. Sukhorukov, A. Kornowski, S. V. Kershaw, H. Möhwald, A. Eychmüller, H. Weller, Adv. Mater., 2000, 12, 333.].

The thermolysis of organomethallic precursors (reaction 2) is used to prepare CdSe [C. B. Murray, DJ. Norris, M. G. Bawendi, J. Am. Chem. Soc., 1993, 115, 8706.] and CdTe [D. V. Talapin, S. Haubold, A. L. Rogach, A. Kornowski, M. Haase, H. Weller, J. Phys. Chem. B., 2001, 105, 2260] nanoparticles. The use of mixtures of coordinating solvents such as hexadecylamine (HDA), trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP) leads to better crystallinity and to narrower size distributions of the nanoparticles in comparison to those prepared in aqueous solutions. Nanoparticles of III-V semiconductors, e.g., InP and InAs can be prepared by the dehalosylilation reaction (3) between InCl₃ and tris(trimethylsilyl)-phospine (-arsine) in a TOP/TOPO mixture or in pure TOP [D. V. Talapin, N. Gaponik, H: Borchert, A. L. Rogach, M. Haase, H. Weller, J. Phys. Chem., 2002, 106, 12659]. The nanoparticle size is controlled by the reaction temperature, duration of heating and the post-preparative size-selective fractionation [C. B. Murray, C. R. Kagan, M. G. Bawendi, Annu. Rev. Mater. Sci. 2000, 30, 545.].

The tetrazole-based stabilizing agents according to this disclosure can be introduced during nanoparticles synthesis, e.g., in the reaction schemes (1-3) or other, by employing tetrazole derivatives as stabilizing agents. Alternatively, the high-quality nanoparticles can be prepared by well established techniques (1)-(3). After the synthesis, the conventional (non-removable) stabilizing agents will be replaced by tetrazole derivatives according to this disclosure by several steps of surface ligand exchange procedure [C. B. Murray, D. J. Norris, M. G. Bawendi, J. Am. Chem. Soc., 1993, 115, 8706.]. Solubility of tetrazole-derivatieves can be tailored by varying substituents at the N1, C2 and/or C5-position. In general, in the direct synthesis of tetrazole-capped nanoparticles the temperature should be maintained below 200-250° C. to prevent decomposition of tetrazoles.

Typically at least about 20 moles of the tetrazole-based stabilizing agent are used to stabilize one molecule of nanocrystalline particles and more typically about 20 molecules to about 200 molecules of the tetrazole per molecule of nanoparticles are used.

The tetrazoles are typically removed by annaling at temperatures of about 100° C. to about 350° C. and more typically at temperatures of about 150° C. to about 280° C.

The films can be sintered simultaneously with or immediately after removing the tetrazoles or in a separate after their removal depending upon the temperatures to be used for the removal and sintering. The sintering can typically be carried out at temperatures of about 200° C. to about 800° C. and more typically at temperatures of about 250° C. to about 500° C.

The nanoparticles with removable stabilizing agents can be used as building blocks for thin film field effect transistors (FET). To be assembled into an FET, the thin (50-100 nm) film of close-packed nanoparticles can be deposited, e.g., by spin-coating, on top of a Si wafer covered with a layer of thermal gate oxide SiO₂ with lithographically patterned Au source and drain electrodes [Thin-Film Transistors, Eds. Kagan, C. R. & Andry, P., Marcel Dekker, New York, 2003; D. B. Mitzi, L. L. Kosbar, C. E. Murray, M. Copel, A. Afzali, Nature, 2004, 428, 299.]. Annealing of the nanocrysal film at elevated temperatures as mentioned above results in removal of stabilizing agents from the nanoparticle surface and sintering the nanoparticles into a uniform film as shown in FIG. 1.

The following are non-limiting examples to further facilitate an understanding of the present disclosure:

EXAMPLE 1

CdS nanoparticles stabilized with 5-aminotetrazole (5-ATz) are synthesized by adding equimolar amounts of dimethylcadmium and bis-(trimethylsilyl)sulfide to a saturated solution of 5-ATz in acetonitrile at about room temperature. In a typical recipe, about 0.2 g 5-ATz are added to about 4 mL of anhydrous acetonitrile and the mixture is stirred under nitrogen atmosphere for about 30 min to form a saturated solution of 5-ATz. About 0.05 ml (0.67 mmol) dimethylcadmium are added to the mixture with stirring. Formation of the CdS nanoparticles is initiated by injection of about 0.132 ml (0.67 mmol) bis-(trimethylsilyl)sulfide under vigorous stirring. The reaction is accompanied by gas evolution. The solution is left stirring at room temperature for about 30 min. The reaction mixture is filtrated through 0.2 micron PTFE filter to remove non-dissolved 5-ATz. The formed CdS nanoparticles form a stable yellow colloidal solution. Transmission electrone microscopy (TEM) shows that small, about 3 nm size CdS nanoparticles assemble into polycrystalline wire-like aggregates shown in FIG. 2.

EXAMPLE 2

A film of CdS nanoparticles stabilized with 5-ATz obtained according to Example 1 is drop-cast on a SiO TEM grid or spin-coated on SiN_(x) membrane for high-resolution TEM investigation. The 5-ATz capped CdS nanoparticles form a dense film with ˜3 nm single-crystalline domains (FIG. 3 a). Electron diffraction data (FIG. 3 b) show that the film is nearly amorphous, with inclusions of very small CdS crystalline domains. Annealing of this film under nitrogen atmosphere for about 1 hour at about 230° C., i.e., slightly above the decomposition temperature of 5-ATz results in a dramatic improvement of the film crystallinity as shown in FIGS. 3 c,d. The annealing results in formation of a polycrystalline CdS film as confirmed both by high-resolution TEM and electron diffraction investigations (FIG. 3 c and d).

The foregoing description illustrates and describes the disclosure. Additionally, the disclosure shows and describes only the preferred embodiments but, as mentioned above, it is to be understood that it is capable to use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the invention concepts as expressed herein, commensurate with the above teachings and/or the skill or knowledge of the relevant art. The embodiments described herein above are further intended to explain best modes known by applicant and to enable others skilled in the art to utilize the disclosure in such, or other, embodiments and with the various modifications required by the particular applications or uses thereof. Accordingly, the description is not intended to limit the invention to the form disclosed herein. Also, it is intended to the appended claims be construed to include alternative embodiments.

All publications and patent applications cited in this specification are herein incorporated by reference, and for any and all purposes, as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. 

1. Nanoparticles coated with a tetrazole represented by the formula

wherein each R individually is selected from the group consisting of H, NH₂, NR′R′, SH, C₁-C₉ alkyl and C₁-C₉ alkyl substituted with at least one member selected from the group consisting of halogen, NH₂ SH and COOH and when substituted with COOH the substitution is on the end carbon atom farthest from the nitrogen of the tetrazole ring, each R′ individually is selected from the group consisting of H and C₁-C₄; and wherein at least one R group is H.
 2. The nanoparticles of claim 1 wherein the tetrozole compound decomposes at temperatures of about 100° C. to about 350° C.
 3. The nanoparticles of claim 1 wherein the tetrazole compound decomposes at temperatures of about 150° C. to about 280° C.
 4. The nanoparticles of claim 1 having a particle size of about 20 nanometers or less.
 5. The nanoparticles of claim 1 having particle size of about 10 nanometers or less.
 6. The nanoparticles of claim 1 which comprise 5-aminotetrazole.
 7. The nanoparticles of claim 6 which comprise CdS.
 8. A method for preparing the nanoparticles of claim 1 which comprises adding the tetrazole during synthesis of the nanoparticles.
 9. A method for preparing the nanoparticles of claim 1 which comprises adding the tetrazole after synthesis of the nanoparticles.
 10. An article which comprises a substrate and a layer of nanoparticles according to claim 1 coated on the substrate.
 11. A method for fabricating an article which comprises depositing on a substrate, a layer of nanoparticles according to claim
 1. 12. The method of 11 which further comprises removing the tetrazole from surface of the nanoparticles.
 13. The method of 12 which further comprises sintering the nanoparticles after removing the molecules containing the tetrazole moiety.
 14. A method for fabricating a device which comprises depositing on a substrate, a layer of nanoparticles according to claim 1, then removing the molecules containing the tetrazole moiety from the surface of the nanoparticles; and then sintering the nanoparticles.
 15. The method of claim 12 wherein the materials is catalytically active
 16. The method of claim 12 where the device is a ferroelectric memory element.
 17. The method of claim 12 where the device is a piezoelectric element.
 18. The method of claim 14, wherein the device is a field effort transistor.
 19. The method of claim 14 wherein the device is a solar cell.
 20. The method of claim 14 wherein the device is a spring exchange magnet.
 21. The method of claim 14 wherein the device is a magneto resistive sensor. 